Random urine calcium/osmolality in the assessment of calciuria in children with decreased muscle mass.

BACKGROUND: Random urine Ca/creatinine (UCa/Cr) is used to estimate 24-hour Ca excretion. However, due to decreased urine creatinine excretion in children with decreased muscle mass (DMM), UCa/Cr overestimates their Ca excretion. OBJECTIVE: To evaluate whether in children with DMM random urine Ca/osmolality (UCa/Osm) can accurately predict hypercalciuria (24-hour urine Ca > 4.0 mg/kg) and at which "cutoff" value. METHODS: 19 children with DMM and 29 with normal muscle mass (NMM), ages 6 - 17 years, were studied. DMM was diagnosed based on clinical findings and decreased serum creatinine, and confirmed by low urine creatinine excretion. Over 24 hours, subjects collected each void separately. After each sample was analyzed, samples of each participant were combined to form a 24-hour specimen from which an aliquot (AL) was obtained; 24-hour urine Ca was first correlated with the corresponding AL Ca/Cr and Ca/Osm. As an internal control, a similar assessment ofproteinuria was conducted. In the next step, AL data were compared with individual urine samples to identify the time of day when a random sample best correlates with AL. RESULTS: The correlation coefficient between 24-hour Ca and AL Ca/Cr in all children was 0.61, in NMM 0.96, and in DMM 0.69 (in all p < 0.001). The correlation coefficient between 24-hour urine Ca and AL Ca/Osm in all children was 0.90, in NMM 0.90, and in DMM 0.91 (in all p < 0.001). In children with DMM, the correlation coefficient of 24-hour protein with AL protein/Cr was 0.75, and with protein/Osm 0.98 (both p < 0.001). Receiver operating characteristic curves showed UCa/Cr as a better predictor of 24-hour Ca > 4.0 mg/kg in NMM, whereas UCa/Osm was a better predictor of hypercalciuria in DMM patients. In NMM, UCa/Cr ratio > 0.20 had sensitivity of 88% and specificity of 96% in detecting 24-hour Ca > 4.0 mg/kg, whereas in those with DMM UCa/Osm (x 10) ratio of > 0.25 had sensitivity of 100% and specificity of 93% in detecting hypercalciuria. It was further found that random urine specimens collected between 9:00 a.m. and 2:00 p.m. best represented 24-hour urine data. CONCLUSION: In children with DMM, UCa/Osm can successfully replace UCa/Cr as a screening tool for hypercalciuria.

Urinary tract infection in childhood. Review of guidelines and recommendations.

Children with urinary tract infection continue to be an important part of the pediatric practice. New uroradiologic imaging techniques like cortical radionuclide scanning and prenatal ultrasonography improved our understanding of the etiology, effect of treatment and outcome of these patients. Evidently, most kidneys at risk are those which already sustained intrauterine damage by obstruction or vesicoureteral reflux. It is the pediatrician's role to minimize ex-utero damage caused by bacterial infection by early diagnosis and appropriate intervention. The introduction of new potent oral antimicrobials limits the need for hospitalization only to the very young infant and the very seriously ill child. Whereas the roles of routine renal ultrasound and cortical radionuclide scan are debatable, all young children and select older children have to be investigated by cystography for possible vesicoureteral reflux. In children with vesicoureteral reflux, long-term antibiotic prophylaxis is required in most children but in a few surgical correction might be indicated. Young siblings of the propositus with vesicoureteral reflux have to be investigated as well for possible reflux. This review covers these and other guidelines and recommendations of diagnosis and treatment of UTI in children at the beginning of the third millennium.

Pneumonia-associated acute glomerulonephritis.

OBJECTIVE: Post-infectious glomerulonephritis typically occurs 7-14days after an infection. However, in several children we observed acute glomerulonephritis (AGN) to develop concurrently with pneumonia. The objective of the study was to delineate the clinical course and outcome of pneumonia-associated AGN. STUDY DESIGN: The hospital database was searched from 1984 - 1999 for c+hildren admitted with both acute pneumonia and AGN, each diagnosis having been made within 72 hours of each other. RESULTS: 11 boys, age 3.8- 12.7 years, were identified. Ten children had lobar pneumonia and I had an interstitial infiltrate. All responded to antibiotic therapy with resolution of fever and respiratory symptoms. Only I child developed an empyema. The mean +/- SD hospital stay was 5.9 +/- 3.9 days. All patients had an abnormal urinalysis with hematuria (gross hematuria in 5), proteinuria and cellular casts. At presentation, 7 children had a serum creatinine > 1.0 mg/dl and creatinine clearance < or = 80 ml/min/1.73 m2; in all, serum creatinine returned to normal and the creatinine clearance was > 80 ml! min/1.73 m2 on follow-up. Nine of the 11 children had a low serum complement C3, 3 of whom also had low complement C4. Anti-streptolysin-O (ASO) titers were elevated in all 10 children tested. Six children developed hypertension and received antihypertensive medications. Only I child was severely oliguric requiring peritoneal dialysis for 4 days. He underwent a kidney biopsy, which showed acute proliferative glomerulonephritis without crescents. Neither a biopsy nor dialysis was performed in the other children. At follow-up, blood pressure, urinalysis and serum complements had normalized in the 9 children in whom follow-up was available. CONCLUSION: Children with pneumonia who are found to have abnormal urinalysis. hypertension, azotemia or oliguria should be evaluated for concomitant glomerulonephritis. In most children, pneumonia-associated AGN runs a benign course and has a good prognosis, however, in some short-term medical intervention may be necessary.

Preservation of bone mass in pediatric dialysis and transplant patients.

Renal osteodystrophy continues to be a major challenge to the physician treating the child with end-stage renal disease (ESRD). The gold standard for the assessment of bone status is bone histomorphometry, which divides bone pathology into 3 main types; high-turnover, low-turnover, and mixed disease. The high-turnover disease, related to hyperparathyroidism, has been the one most extensively investigated; however, optimal therapy, especially in the growing child, is yet unclear. Overzealous treatment might result in adynamic bone disease (an extreme example of low-turnover disease), and further interference with statural growth. Pre-existent bone disease after kidney transplantation seems to worsen immediately, probably because of the high dose of corticosteroids used. In children who attain normal kidney function in the allograft, bone status seems to improve over time. Little is known about bone in transplanted patients with reduced glomerular filtration rate (GFR). The correlation between bone histology and its main surrogates, bone remodeling markers and bone mineral density, is yet unclear, but it might serve to follow the progress of an individual patient. New therapeutic modalities aimed at suppressing hyperparathyroidism, and consequently bone resorption, as well as agents directly attenuating bone resorption, should be further investigated for their effect on bone in patients with ESRD or after transplantation. Similarly, agents stimulating bone formation, particularly growth hormone, require further attention for their potential to improve bone status. Bone health and the child's somatic growth at ESRD or after kidney transplantation are closely related, and therapy should be aimed at achieving optimal results for both.

Antacid-induced rickets in infancy.

A 3-month-old premature infant presented with a "soft skull." Clinical and radiologic findings confirmed the diagnosis of rickets. Biochemistry revealed normal serum parathyroid hormone (PTH) and undetectable urine phosphate. These findings combined with a history of 5-6 weeks' treatment with high-dose aluminum-rich antacid established the diagnosis of antacid-induced rickets. Discontinuation of the medicine combined with phosphate and vitamin D supplementation resulted in quick resolution of all clinical, radiologic, and biochemical abnormalities. Our patient demonstrates that in premature infants antacid-induced rickets can develop within a few weeks; normal serum PTH concentration and hypophosphaturia are highly indicative of the diagnosis, and contrary to the situation in adults in whom hypercalciuria has been often described, in infants hypocalciuria is more commonly observed. Pediatricians should avoid or minimize the use of aluminum-containing antacids, and when used, carefully monitor mineral metabolism.

Measurement of urinary concentration: a critical appraisal of methodologies.

The measurement of urine concentration provides information concerning the kidney's ability to appropriately respond to variations in fluid homeostasis. It also assists in the interpretation of other tests performed on the same urine specimen. The gold standard of estimating urinary concentration is the measurement of its osmolality; however, this procedure is not readily available to the practicing physician. Therefore, urine concentration is usually determined by measurement of its specific gravity (SG), which provides a fair estimate of urine osmolality. Over the years numerous tests have been developed to measure urine SG in a simple, quick, reliable and easily available method. These tests measure SG either directly (e.g., gravimetry) or by indirect methods (e.g., refractometry and reagent strip). All these tests have certain limitations based on their underlying physical principles. Specific gravity as measured by refractometry is influenced by proteinuria, such that for each 10 g/l protein the SG increases by 0.003. SG is also influenced by glucosuria such that it increases by approximately 0.002 per 10 g/l glucose when compared with urinary osmolality. Unlike osmolality, which is only affected by the number of particles, refractometry is affected by number, mass and chemical structure of the dissolved particles; hence large molecules like radiographic contrast or mannitol will increase SG relative to osmolality. The reagent strip is minimally affected by glucose, mannitol or radiographic contrast. However, it is affected by urinary pH such that only urine in the pH range of 7.0-7.5 can be correctly interpreted. The measurement of SG by reagent strip is based on the ionic strength of the urine and thus is significantly affected by the ionic composition of the urine and by proteins which have an electric charge in solution. In our experience, SG measured by the refractometer is consistently more accurate than the reagent strip. For the clinician who is interpreting urine SG results, it is important to be aware of these limitations and understand the reasons for possible potential errors of each particular method.

Proteinuria and focal segmental glomerulosclerosis in severely obese adolescents.

OBJECTIVE: To describe the clinical and laboratory features of obesity associated proteinuria and focal segmental glomerulosclerosis. STUDY DESIGN: The patients were seen over a 12-year period at two large children's hospitals. Renal biopsies, performed for the diagnosis of unexplained heavy proteinuria and prepared for light, immunofluorescent, and electron microscopy, were read independently by two pediatric pathologists. Blood pressure, body mass index, serum levels of creatinine, albumin, and cholesterol, and 24-hour urinary protein were measured. RESULTS: Seven African American adolescents were identified with obesity-associated proteinuria, which was characterized by severe obesity (120 +/- 30 kg), markedly elevated body mass index (46 +/- 11), mild hypertension (134/74 +/- 10/18 mm Hg), slightly low to normal serum albumin levels (3.6 +/- 0.2 g/dL), moderately elevated serum cholesterol levels (196 +/- 60 mg/dL), and elevated 24-hour protein excretion (3.1 +/- 1.3 g/dL). Calculated creatinine clearance was normal in 6 patients and decreased in one. Typical renal histologic features included glomerular hypertrophy, focal segmental glomerulosclerosis, increased mesangial matrix and cellularity, relative preservation of foot process morphology, and absence of evidence of inflammatory or immune-mediated pathogenesis. One patient showed a dramatic reduction in proteinuria in response to weight reduction. Three patients who were given angiotensin-converting enzyme inhibitors had reduced urinary protein losses from 2.9 g to 0.7 g per day. One patient developed end-stage renal disease. CONCLUSION: Obese adolescents should be monitored for proteinuria, which has distinct clinical and pathologic features and may be associated with significant renal sequelae. Such proteinuria may respond to weight reduction and/or treatment with angiotensin-converting enzyme inhibitors.

Normal urinary calcium/creatinine ratios in African-American and Caucasian children.

A random urine calcium/creatinine ratio (UCa/Cr) is of practical use in screening for hypercalciuria. However, due to worldwide variations, reference values for the pediatric population are not yet well established. Furthermore, no study has been conducted to establish normal UCa/Cr values in young African-American (AA) children. It has also been previously reported that an elevated UCa/Cr is related to a high urine Na/K ratio (UNa/K). The objectives of the present study were: (1) to set normal values of random UCa/Cr by age and race in the pediatric population of Metropolitan Kansas City, (2) to identify potential racial differences in UCa/Cr between Caucasian (CS) and AA children, and (3) to determine the relationship between UCa/Cr and UNa/K in healthy children. A total of 368 healthy children of both genders were enrolled in the study. They were divided into four age groups as follows: (1) <7 months, (2) 8-18 months, (3) 19 months to 6 years, and (4) 7-16 years. Each group was subdivided into AA and CS. A non-fasting random urine specimen from each subject was analyzed for Ca, Na, K and creatinine. The median UCa/Cr values for AA were: (1) 0.13, (2) 0.09, (3) 0.06, and (4) 0.04 and for CS they were (1) 0.26, (2) 0.11, (3) 0.10, and (4) 0.09. The data showed a strong inverse relationship between UCa/Cr and age, the youngest children demonstrating the highest UCa/Cr. In each age group, UCa/Cr in CS exceeded the corresponding value in AA. The age-dependent 95th percentiles of UCa/Cr values for CS were (1) 0.70, (2) 0.50, (3) 0.28, and (4) 0.20 and for AA they were (1) 0.38 and (3) 0.24. Due to outliers, the 95th percentile could not be established for the other two AA subgroups. The relationship between UCa/Cr and UNa/K was found to be extremely weak in both AA (r2=0.00005) and CS (r2=0.02). On the other hand, a strong linear correlation was observed between UNa/K and age (CS r2=0.23, P<0.001, AA r2=0.19, P<0.001), explaining in part the lack of correlation between UNa/K and UCa/Cr. We conclude that the child's age, ethnicity and geographic location should be taken into consideration when assessing UCa/Cr ratio. Contrary to what has previously been reported in hypercalciuric children, no significant relationship was found between UCa/Cr and UNa/K in healthy children.

Synaptopodin expression in idiopathic nephrotic syndrome of childhood.

BACKGROUND: Synaptopodin is a proline-rich protein intimately associated with actin microfilaments present in the podocytes' foot processes. We investigated for synaptopodin expression in children with idiopathic nephrotic syndrome (INS), including minimal change disease (MCD), diffuse mesangial hypercellularity (DMH), and focal segmental glomerulosclerosis (FSGS); in children with congenital nephrotic syndrome of the Finnish type (CNF); and in normal kidney tissue. In particular, we examined whether an association exists between synaptopodin expression in podocyte cells and the response to steroids in INS, and whether synaptopodin expression can predict FSGS upon the initial kidney biopsy in children who progress from MCD or DMH to FSGS. METHODS: Immunohistochemistry was performed for synaptopodin expression on renal tissues from MCD (N = 18), DMH (N = 7), FSGS (N = 13), CNF (N = 9), and normal children (N = 7). Synaptopodin expression in nonsclerosed glomeruli was quantitated by computerized image analysis on the Optimastrade mark software for both luminance (L) and percentage of glomerular area (A). RESULTS: Synaptopodin expression was absent in areas of sclerosis. In nonsclerosed glomeruli, synaptopodin was significantly less expressed in all groups of INS and in CNF compared with normal (P < 0.0001 for both L and A, in each MCD, DMH, FSGS, and CNF). In INS, synaptopodin expression decreased in order from MCD to DMH to FSGS, reaching statistical significance between MCD and FSGS (P = 0.001 for L and P = 0.05 for A). Greater synaptopodin expression in podocytes was associated with a significantly better response to steroid therapy (P < 0.05 for both L and A). On the other hand, the expression of synaptopodin did not predict progression of MCD or DMH to FSGS. CONCLUSION: We conclude that measurement of synaptopodin has the potential to be used as a marker to study the alteration in podocyte cell and response to therapy in INS.

Podocyte proteins in Galloway-Mowat syndrome.

Galloway-Mowat syndrome is an autosomal recessive disorder characterized by early onset nephrotic syndrome and central nervous system anomalies. Mutations in podocyte proteins, such as nephrin, alpha-actinin 4, and podocin, are associated with proteinuria and nephrotic syndrome. The genetic defect in Galloway-Mowat syndrome is as yet unknown. We postulated that in Galloway-Mowat syndrome the mutation would be in a protein that is expressed both in podocytes and neurons, such as synaptopodin, GLEPP1, or nephrin. We therefore analyzed kidney tissue from normal children (n=3), children with congenital nephrotic syndrome of the Finnish type (CNF, n=3), minimal change disease (MCD, n=3), focal segmental glomerulosclerosis (FSGS, n=3), and Galloway-Mowat syndrome (n=4) by immunohistochemistry for expression of synaptopodin, GLEPP1, intracellular domain of nephrin (nephrin-I), and extracellular domain of nephrin (nephrin-E). Synaptopodin, GLEPP1, and nephrin were strongly expressed in normal kidney tissue. Nephrin was absent, and synaptopodin and GLEPP1 expression were decreased in CNF. The expression of all three proteins was reduced in MCD and FSGS; the decrease in expression being more marked in FSGS. Synaptopodin, GLEPP1, and nephrin expression was present, although reduced in Galloway-Mowat syndrome. We conclude that the reduced expression of synaptopodin, GLEPP1, and nephrin in Galloway- Mowat syndrome is a secondary phenomenon related to the proteinuria, and hence synaptopodin, GLEPP1, and nephrin are probably not the proteins mutated in Galloway-Mowat syndrome.

Sieving coefficient inaccuracies during hemodiafiltration in patients with hyperbilirubinemia.

Hemodiafiltration has assumed an important role in the supportive therapy of critically ill patients. The viability of the filter used for hemodiafiltration can be monitored by estimating the sieving coefficient of small molecules such as creatinine and/or urea. We report on three patients with severe hyperbilirubinemia whose creatinine sieving coefficient was spuriously elevated as a result of discordance in the accuracy of creatinine measurement in plasma and ultrafiltrate respectively. This discordance was a consequence of lack of bilirubin clearance during hemodiafiltration. As a result, while the plasma creatinine determination by the kinetic Jaffe method was negatively influenced by the hyperbilirubinemia, the ultrafiltrate creatinine was not. This report is the first to document the lack of bilirubin clearance during hemodiafiltration and its impact on the calculation of sieving coefficient based on creatinine. The use of urea as the solute for determining the sieving coefficient allows for an accurate estimate and provides a valid means of monitoring this parameter in the setting of hyperbilirubinemia.

Pediatric biopsy of a single native kidney.

Technological improvements have reduced the frequency of complications in children receiving a percutaneous renal biopsy. No study has systematically compared the safety of open and percutaneous kidney biopsy. Yet many nephrologists consider a single native kidney an absolute contraindication to percutaneous biopsy. We have established an international registry of single native kidney biopsies in children and we now report our early results. Eight biopsies are included. Seven patients had percutaneous biopsies and one an open biopsy. None of the patients had major complications, and adequate tissue was obtained from all. Our limited experience indicates that the presence of a single native kidney is not an absolute indication for an open approach. We encourage our colleagues to report to the international registry in order to further document the safety of percutaneous biopsy of the single native kidney in children.

Success and safety of same-day kidney biopsy in children and adolescents.

Renal biopsy is crucial for the diagnosis, management, and monitoring of many kidney diseases. Although percutaneous renal biopsy is considered a routine safe procedure in children, the optimal length of in-hospital observation following the procedure is not yet known. We prospectively studied two comparable groups of children to compare the success and safety of performing native renal biopsy as an outpatient procedure versus keeping the children hospitalized post biopsy. Doppler ultrasonography of the biopsied kidney was performed approximately 2 weeks after the procedure. For 40 children the biopsy was performed on a same-day basis (study group) and another 15 children were kept for overnight observation (control group). All biopsies yielded adequate tissue for histopathological diagnosis. There was no difference between the two groups in the amount of reported pain and analgesics used after the procedure. Only 1 child in the study group was readmitted 5 days after the biopsy for 48 h, but no major complications were detected. The incidence of post-biopsy intra- or perirenal hematoma detection by sonography was not statistically different between the two groups (39% study group, 43% control group). Follow-up imaging studies were performed on 10 of the 20 children who had an early post-biopsy hematoma and all were completely normal. Patients and their families appreciated being discharged home the same day. In addition, total charges for hospitalization were significantly less for the study group than the control group. We conclude that in selected patients, same-day discharge after renal biopsy may be performed safely without an increased risk of complications.

C1q nephropathy presenting as rapidly progressive crescentic glomerulonephritis.

C1q nephropathy is an immune complex glomerulonephritis defined by the presence of mesangial immunoglobulins and complement deposits, most notably C1q, and the absence of clinical and laboratory evidence of systemic lupus erythematosus. Histology in C1q nephropathy is characterized by a slight to severe increase in mesangial cellularity and matrix, with or without segmental sclerosis. C1q nephropathy usually presents with nephrotic-range proteinuria in older children and young adults, and has a poor response to steroids. Patients may have decreased creatinine clearance at presentation, but progression to end-stage renal disease (ESRD) is slow. Severe crescentic glomerulonephritis has not been reported in C1q nephropathy. We describe a 3-year-old Hispanic girl who presented with renal insufficiency. Kidney biopsy showed C1q nephropathy with severe crescentic glomerulonephritis. The clinical and serological evaluation ruled out systemic lupus erythematosus or other immunological or infectious etiologies. In spite of immunosuppressive therapy, she progressed to ESRD within 14 weeks and is currently on chronic peritoneal dialysis. The atypical features of C1q nephropathy observed in our patient, which have not been described in earlier reports, are an early age of onset, severe crescentic glomerulonephritis, and rapid progression to ESRD. C1q nephropathy should be added to the differential diagnosis of glomerulonephritis in young children and in the patient with crescentic glomerulonephritis.

Idiopathic hypercalciuria of childhood: 4- to 11-year outcome.

Apart from a minority with urolithiasis, the majority of children diagnosed with idiopathic hypercalciuria present with macro- or microhematuria, abdominal or back pain, or voiding symptoms. With dietary and pharmacological interventions, most such children become asymptomatic and are lost to follow-up, hence their long-term outcome is unclear. In the present study, we evaluated the status of 14 males and 19 females aged 8-17 years (mean 11.9 years, median 11.2 years) 4-11 years (mean 6.9 years, median 6.5 years) after the initial diagnosis of idiopathic hypercalciuria not associated with urolithiasis. A questionnaire was answered and two random urine samples provided 3-4 weeks apart were analyzed for calcium (Ca), sodium (Na), potassium (K), and creatinine (Cr). Urine Ca/Cr ratio > or =20.21 (mg/mg) was defined as hypercalciuria. At the time of the study none were under follow-up, although 7 children were still exhibiting voiding symptoms. No child developed clinical urolithiasis. Based on the first urine specimen, 16 of the 33 (48.4%) were hypercalciuric. Their 2nd urinalysis showed persistent hypercalciuria in 8 and normocalciuria in 8. Urine Na/K ratio (mEq/mEq) decreased in the latter 8 from 5.08+/-2.67 to 3.03+/-2.23 (P<0.05). Of the 17 initially normocalciuric children, 5 did not submit a 2nd specimen, 11 remained normocalciuric, and 1 became hypercalciuric with an increase in urine Na/K ratio. Twenty-three children (all 8 persistently and 9 intermittently hypercalciuric plus 6 normocalciuric) were studied by ultrasonography. Only in 1 asymptomatic persistently hypercalciuric child was a single small renal calcification noted. Introduction of a low-Na/high-K diet in 7 persistently hypercalciuric children resulted in a decrease in UNa/K ratio from 7.34+/-2.15 to 4.14+/-3.09 (P<0.01) and UCa/Cr ratio from 0.25+/-0.04 to 0.13+/-0.03 (P<0.01). We conclude that even though over time most hypercalciuric children become asymptomatic, many remain hypercalciuric. Further follow-up is required to ascertain whether these children are at risk of developing kidney stones. If they are at risk then long-term compliance with a low-Na/high-K diet might be beneficial, as it can normalize calciuria in the majority of these children.

Tenckhoff catheters prove superior to cook catheters in pediatric acute peritoneal dialysis.

Peritoneal dialysis (PD) is the most common form of renal replacement therapy in infants and young children with acute renal failure (ARF). The two most commonly used catheters for performing acute PD are the Cook catheter (CC), placed at the bedside, and the surgically placed Tenckhoff catheter (TC). In the present study, we compared the complications and survival rates of the two catheters. The records of 59 children (age, 1 day to 16.7 years) who underwent PD for ARF from March 1989 through June 1999 in our hospital were reviewed. The initial (primary) catheter was a TC in 22 patients and a CC in 37 patients. The age of the patients who received a primary TC (2.8 +/- 4.5 years) was no different than the age of those with a primary CC (1.4 +/- 2.0 years; P = not significant). The duration of use (mean +/- SD) of TCs (16.5 +/- 14.2 days) was significantly greater than the duration of CC use (4.9 +/- 4.2 days; P < 0.001). Only two patients with a TC (9%) developed complications, whereas 18 patients with a CC (49%) developed complications, 13 of whom required catheter replacement (P < 0.01). Thirty-five patients (59%) recovered renal function after undergoing dialysis for 11.5 +/- 8.0 days. Twenty-three of those patients (66%) required dialysis for more than 5 days. Only 4 patients with a primary CC had successful completion of dialysis without catheter-associated complications compared with 15 patients with a primary TC. Kaplan-Meier survival analysis showed that by day 6 of dialysis, only 46% of primary CCs were functioning without complications compared with 90% of TCs that were free of complications. We conclude that the use of a CC is associated with significantly more complications than a TC, and nearly one half of the CCs are likely to be nonfunctional beyond 5 days of dialysis, at a time when two thirds of the patients are still expected to be undergoing dialysis. Therefore, when possible, a TC should be the catheter of choice when initiating acute PD in children. In those patients for whom a CC is chosen as the initial catheter, an elective change to a TC should be considered once dialysis is expected to extend beyond 5 days.

Effect of thiazide on established furosemide-induced nephrocalcinosis in the young rat.

A previous study on furosemide-induced nephrocalcinosis (NC) showed only partial resolution of the calcifications after discontinuation of the diuretic. We investigated whether treatment with chlorothiazide (CTZ) will expedite the resolution of established furosemide-induced NC. Seventy-eight weanling male Sprague-Dawley rats were divided into eight groups. Three groups were studied for 1 week: A, control; B, furosemide 40 mg/kg per 24 h; C, CTZ 100 mg/kg per 24 h. Five groups were studied for 5 weeks: D, control; E, F, G, furosemide 40 mg/kg per 24 h for 1 week followed by 4 weeks of observation (E), CTZ 50 mg/kg per 24 h (F), and CTZ 100 mg/kg per 24 h (G) and; and CTZ 100 mg/kg per 24 h (H) for 5 weeks. At the end of each study period urine and blood were collected, one kidney was studied histologically and the contralateral ashed for quantitative calcium (Ca) analysis. Animals in group B developed NC with a kidney Ca content of 1,844 +/- 203 micrograms/g dry tissue compared with group A 248 +/- 86 (P < 0.05) and group C 256 +/- 56 (P < 0.05). There were no differences among the three groups with regard to creatinine clearance, urine phosphate (P) or Ca excretion, although the latter tended to be lower in group C. Animals in group E showed a reduction in the magnitude of NC, with kidney Ca of 550 +/- 398 micrograms/g dry tissue, which was lower than in group B (P < 0.05) but still higher than in groups D (140 +/- 27) (P < 0.05) or H (162 +/- 63) (P < 0.05). Kidney Ca content in groups F (497 +/- 142) and G (489 +/- 271 micrograms/g dry tissue) was similar to that in group E. There were no differences among the five groups with regard to creatinine clearance or urine P excretion. Urine Ca excretion was significantly lower in groups F and G than groups D and E. We conclude that once established, NC caused by furosemide is not affected by CTZ therapy in spite of the anticalciuric property of the latter.

Bilateral nephrectomy reverses hypothyroidism in congenital nephrotic syndrome.

A state of biochemical hypothyroidism is commonly seen in infants with congenital nephrotic syndrome (NS) and therefore the current recommendation is to place all patients with congenital NS on supplemental thyroid preparations. We report our experience in five children with congenital NS in whom thyroid supplementation was discontinued following bilateral nephrectomy and initiation of renal replacement therapy. Immediately after nephrectomy, thyroid function tests normalized, except serum thyroid-stimulating hormone (TSH) concentration, which initially rose, but normalized later. This observation supports the hypothesis that hypothyroidism in these patients is secondary to the chronic massive proteinuria and is not the result of a defect intrinsic to the thyroid gland itself. Abatement of massive proteinuria enables discontinuation of thyroid supplementation, and a transient rise in TSH in the early post-nephrectomy stage should be potentially expected.